Production of pure alumina



Patented" Dec. 1 6, 1924.

--: onireo STAT S PATENT OFFICE.

e v A i HEINRICH AND GUSTAV M'UNCH, OF GRIESHEIM-ON THE-MAIN, AND FRITZ ROSSTEUTSCHEB, OF SCHWANHEm-ON THE-MAIN," GERMANY, ASSIGNORS, BY ASSIGNMENTS, TO. AMERICAN LURGI CORPORATION, OF NEW YORK,

- N. Y., A CORPORATION OF NEW YORK.

PRODUCTION OF PURE AL UMINA.

I NoDrawing.

'a'lii'miniferous materials It is well known that by introducing zmhydrous hydrochloric acid gases of specially higli/ ;concent1ation into solutions obtained in the-well known manner of treating raw 'alum'iniferous materials with hydrochloric acid, aluminium chloride can be -prec1p1- tated and that this precipitated aluminium washing.

'- hloride" can be 'freed fron iron by systematic iThis method otseparation necessitates the useeof anhydrous hydrochloric acid gases of concentration, which are difiicult and "expensive to produce in practice.

Extensive investigations haveshown that i the same results may be obtained in a ve simple and efi'ective' manner and that the aluminum chloride may be separated from the. iron with even far less concentrated hydrochloric acid. According to the present inventiidn t he solutions containing aluminium chloride, iron and other "foreign chlorides, obtainedby treating for example calacid; The hydrochloric acid solution required for this purpose amounts to only one 1 quarter or less of the minimum required in chloride.

'cincd clay with hydrochloric acid, are evap orated' in a suitable apparatus, until a syrupy crystal sludge is obtained, whichis then coole rafter which the mother liquor is scparat'edfrom the salt sludge'by filtration with suction. gIn order to obtain the aluminium chloride, containing water of crystallization, ina pure 'state, it has been found entirely suflicient if the salt mixture obtained in the,

evaporation in .the; above idescribedfmanner, is: repeatedly washed .with hydrochlor c the process of salting out the aluminium Thus, according to the present process, the chloride is obtained in a pure form in a simple manner and with a con- Application filed October- 6, 1922. serial No. 592,875. l m

acid. The process can be still further improved and a separation of the aluminium chloride from iron efie'cted in a perfect manner with chloricacid solution which is almost or comgletely saturated with aluminium; chloride. uch-a solution gives a powerfurwashing effect and the crystalline aluminium chloride is practically insoluble in it. i

In carrying out our invention we have obtained 'good results in proceeding: for in-' stance as follows: i v

Oalcined clay is treated with hydrochloric tion is evaporated until-a crystal sludge is formed which substantially contains the alu-- minium chloride in the crystallinestate, and

siderable economy in the use, 6f hydrochloric acid. The greater part of the filtered solu-.

the iron chlorideflin solution:- -i This? crystal sludge is filtered with-suction, and methodically washed with' solutions obtained by treating and enriching the other pmof the mixture of hydrochloric acid and .w'ater-vaabove-mentioned filtered solution with a pour obtained by the'zthermic decomposition of the isolated gore aluminium chloride obtained. from a washing procedure theiiron chloride reextent. "Finally thecrys talsludgeis washed acid is preferably obtained fromand'thiir part of the" waste ggvses of the piocess of: "e composition df-alu nmi'um'chlcfide; b coI densing or washing with watei cir revious operation. By; this I v moved from the -crystal' sludge -to,

with hydrochloric acid freeiromiromxvhioh- 'ute v i hydrochloric acid 1 The; iesulting ;was11: j 11 nor is used'as acideni'rchedorgaturated; with aluxmhlum chlorlde as longhs-lheiron content permits. 'l he acid wash'and'motfien liquors containing alum nium and iroirclrlo "f rides are, accordmgto their content, either added to the acid Yus'edfor. treating'ra'w ma-fl i -terial," or used as washing."liquors. en

the solutions become-rich-in iroIi chloride,

they are finally subjected to ther nic decomgition, in order to regenerate the hydro- Z loric acid contained therein. From the alumina is produced.

aluminium chloride obtained, pure This process makes it possible to-einploy a comparatively dilute hydrochloric acid gas containing air and water vapour, such as is obtained from the thermic decomposition carried out, for example in a rotary fur-1 nace, whereas the former processes necessi' v tated the employment of'eoncentrated hy-=' drochloric acid gases which could, as a} rule,

only be obtained from more or less moist.

gases by drying with sulphuricjacid,

Moreover, .according to the present proc-i ess, by enrichingwith hydrochloric acid the solution used for treating raw aluminifer- 'ous material and by re-usi'nd-the latter for treating further amounts 0 clay, a more concentrated aluminium chloride solution can be obtained from .the beginning, so thattained by filtering with suction isreturned into the evaporation pans, while the acid are employed for absorbin a considerable economy in evaporating costs is attained-. It is, of course,opossibleif desired, to dispense with the decomposition of thealuminium chloride produced intoalumine, and to use the crystallized aluminium chloride as finalproduct, in which case, a, larger amountof-hydrochloric acidmust be employed. I Emample: OflOOO kgs. of a solution obtained by treating clay or the like with hydrochloric acid and which may contain for" instance 350 kgs. AlCl +6aq.',- about two thirds are'concentrated by evaporation. and

cooled. The resulting mass of crysta sis separated from the .motlier liquor, and

washed with hydrocholoric-acid or solutions containing same, the washing requiring.

about kgs. HCL Themother liquor obemployed for washing is' used anew ina systematic way. The salt, which 'is still moist, is freed from the adhering acid liquid by drying. About per cent, that is about 185 kgs. of chloride are obtained in this manner and are either used assuch or are subjected .to 'thermic decomposition, the mixture of hydrochloric acid and steam, which is thus formed, being first caused to' pass through a towersprinkled with the last third of the original solution. (Further towers the rest of hydrochloric acid "gases whic are converted into -pure hydrochloric acid.) The solution or, in View of its being which ultimately contains a high percentage of free hydrochloric acid is .now used for.

treating further quantities of clay or the-like aluminium chloride 1t maybe used as a first washin liquor fonfithe crystalline mass 0btaine forthe treatment of fresh raw material. In

either, case, the enriching with hydrochloric acid results m an increased concentration of the solutions employed for such treatment, thus rendering the evaporation of the chloride solution more economicalthan if the hydrochloric acid obtained by the. thermic dehighly saturatedwith d y evaporation before being employed composition were absorbed inwater and em.- w

plo'yed in the treatment of raw material;

We wishit to be understood-that we'do' not desire to' be limited to the exact sequenceof steps ,norto the exact proportions dc scribed, as obvious modifications. will read-- ilyoccur to 'a person skilled inthe'art.

Weclaim: 4

, 1. The process which comprises treating aluminiferous material with hydrochloric acid, concentrating by evaporat fin part of the solution thus obtained, until a'sludge of aluminium chloride crystals separates out, introducing the hydrochloric acid gas resultingfromthe thermic decomposition of alu-' mlniumchloride crystals of aprior opera tion into "the non-eva orated, part of saidmg from 'thethermic tion into the non-evaporated partof said s0 this solution said I 2. The process which comprises treating aluminium chloride crystals'separates' out,- introducing the hydrochloric acid gas resultdecomposition of aluminium chloride crystals ofa prior opera lution, ywashing' withthis solution said drochloric sludge of aluminium chloride crystals, there v after-washing the same with acid free from iron, and then sub ectingsaid v washedsludge of crystals to thermic decom position. i

l The "w h comprisestrea i iiialumi'niferous, material with 'hydrochloric acid, concentrating by evaporation part of the solution thus obtained, until a sludge of.

aluminium chloride crystals se arates out,

introducing the hydrochloricaci gas resultmg from the'thermic decomposition of aluminium chloride crystals of a prior operation into the non-evaporated. part of said solution, washing with this solution said sludge of aluminium chloride 0 stals, thereafter washing the same with h acid free from iron obtained by condensing part ofthe acid gases resulting in said therydrochloric mic decomposition, and then subjecting said, washed sludge ofcrystals to thermicdecon'rposition.

4. Process which comprises treating jaluminiferous material with a solution containin hydrochloric acid and aluminium-ch10 rid e whereby a crudeisolution of aluminium chloride is roduced, evaporating a portion of said crud; solution until a sludge of aluminium chloride crystals is produced, sepafrom motherliquo'r, washing the separated aluminium chloride crystals with a solution ucing hydrochloric acid gas into the remainder ofsaid crude solw.

produced by introd rating the crystallized aluminium chloride 1,51e,sso

tion and using the resulting washliq uors for treating aluminiferousi materialjin a subsequent operation, further washing the separated aluminium chloride crystals with a solution of hydrochloric acid free of iron p gas in aportion of the crude solution of aluminium chloride of a subsequent operaond washing 013' the j acid, concentrating by aluminium "chloride. crystals of a prior op- V f and. g

11. Process which comprises, evaporating tion to produce a solution of hydrochloric acid and aluminium chloride for use for the first washing of separated aluminium chloride crystals in said subsequentoperation, and 'dissolvin the remainder -of said evolved hydroc lorie acid gas in water for the preparation of a 'solution of hydrochloric acid free of iron for use in the secaluminium chloride crystals in said subsequent operation.

5. The process which comprises treating aluminiferous material with hydrochloric evaporation part of the solution thus obtained until: a sludge of aluminium chloride crystals separates introducing hydrochloric 'acid gas re-,

out sulting' from thethermic decomposition of eration into. the nen-evaporated-i-part o-- "saidfsolution, washing with this solution said sludge. of aluminium chloride crystals,

fusing the washings for treating alumunferfous material in a subsequent operation, and then subjecting said washedjs'ludge of guys-- tals to thermic decompos1tion.

6. The-process which cprhprises treating aluminiferous 'material withjh drochloric acid, concentrating by -eva gioratlon part of the solution thus obtained in il a sludge of.

aluminium chloride crystals separates out,

introducin hydrochloric acid-gas resulting from-the t ermic decomposition of alumininto the non-evaporated ,ar

ium chloride crystals of a griorkoperation tion, washing with this so ui'iou-said sludge chloride crystalsf'using the rial in a subsequent operation, thereafter washing the said sludge withhydrochloric acid solution free from iron obtained by'condensing. part .of the acid *fi'om said thermic decompos1tion, using the gases resulting resulging washings for washing a sludge of alum niumchloride crystalsin a subsequent operation, andlathen subjecting said washed sludge of crystals to thermic dGCODIPOSi'. tion. 21 4 '7. The'proce'sslwhich comprises evaporating a crude solution of aluminium ch oride at atmospheric'f pressure until a crystal sludge e is i a et s th rrs al ied v ulumlnium chloride,

"atmospheric pressure -from mother liquor,

' 20% of hydrochloric acid.-

15, Process aluminium, chloride from mother liquor,- washing the separated crystals with a solution ,of hydrochloric acid, and subjecting the washed crystals'to thermic decomosition.

8. The process which comprises washing crystals of aluminium chloride with a sod lution of hydrochloric acid substantially and subjecting the washed crystals to ther mic decomposition.

9. The process which comprises evaporating a crude solution of aluminium chloride until a sludge of aluminium chloride crystals is formed, Washing said sludge with a solution prepared by dissolving hydrochloric acid resulting from the thermic'decomposition of aluminium chloride crystals of a prior operation in a crude solution of and subjecting a the washed sludge of crystals to (her-mic decomposition.

10. Process which comprises, evaporating a solution of aluminium chloride at atmospherlc pressure, separating crystallized aluminiumchloridc from mother liquor, and

washing the separated aluminium chloride crystals with ,a solution of hydrochloric a solution containing aluminium chloride at until a crystal sludge Hit) is formed, separating the crystallized aluminium chloride from mother liquor by filtration, and washing the separated aluminium chloride crystals with a soluton of hydrochloric acid.

los

12. Process wh ch comprises, evaporating a crude solution; containing aluminium chloride at atmospheric pressure until a crystal sludge isforin'ed, separating the crystallizedvaluminium c oride from mother liquor, washin the separated aluminiumchloride crysta s with a relatively dilute solution of hydrochloric acid substantially saturated with aluminium chloride, and

1 thereafter washing said crystals with a solution of hydrochloric acid free from iron.- Process which comprises, evaporating a crude' solution containing aluminium chloride until a crystal sludge is formed, separating the crystallized aluminium chloride I and washing the separated aluminium chloridc crystals with a solutionv containing not more than about" .14. Process whichf,comprisea 'ashing aluminium chlorid hrystals with a solution of hydrochloric'acid containing aluminium chloride.v g i which comprises, washing aluminium chloride crystals with a-solut-ion sae- ],8'L'Process which comprises, washing] of hydrochloric acid substantially satnrated with aluminium, chloride.

I 16.- Process which comprises, washing aluminium chloride crystals with a solution containing aluminium chloride and about of 'hydrochloric acid.

.l7. Process which comprises, washing aluininium chloride crystzils with n solution containingi'about 20% offlhydrocholoric. acid and 'substantiaIL saturated with aluminium.

' tion only of said solution until analum-inium chloride crystal sludge is formed, sepa- -rating the crystallized aluminium chloride almniniunrchloride crystals with a. solution of hydrochloric acid containing aluminium chloride,' and thereafter washing the crystalswith a solution of hydrochloric acid vfree from iron..-

-19. Proc'ess"whichcomprises, washing a batch of alumini'un'i chloride crystals with a. solution of hydrochloric acid containing aluminiuinchloride, thereafter washing said batch, of crystals with a solution of hydro- "chlonicfacidjfree from iron, and using the resultin vvashing liquors as the solution of hydroch oricacid free from iron, and using' theresulting washing liquors as the solu I batch of aluminium chloride tionof hydrochloric acid containing alumini-chloride for the firstwashing of another batchfof aluminium chloride crystals;

washing I crystals with a solution containing about 20% of Process which comprises,

hydrochloric acid and substantially saturated with aluminium chloride, thereafter \vashing said-hatch of crystals with a rela- 3 tivelyconcentrated solution of-hydrochloric acid free from iron, and using the resulting jvash liquors for the first washing of hydrochloric acid, evaporating a portion .of

aluminiferous material with a-solution oi the" resulting solution containing aluminium chloride until an aluminium'chloride cr stal tures. another batch of aluminum chloride crystals. 21. Process which comprises, treatin aluminium chloride from mother liquor, dis- I solving hydrochloric acid 111 the remainder of hydrochloric'acid, separating the'resulting solution containing aluminium chloride Process which comprises, treating from undissolved residue, evaporating a porfrom mother liquor, dissolving hydrochloric acid in'the remainder of said solution, washing the separated aluminium chloride crys tale with the resulting solution ofalum1n ium chloride and hydrochloric acid, and, using the resulting wash liquors for treat-' ing raw aluminifero'us material.

a portion only of the resulting solutionlcon-v taining aluminium chloride until a sludge of aluminium chloride crystals is formed, dis-' solving hydrochloric. acid inv the remainder o of said solution, washing; said aluminium chloride crystals. with the resulting'solution,'

using the resulting wash liquor for treating;

raw aluminife'rous,fiiaterial -further wash ing' said aluminium chloride or stills vith a.

solution of; hydrochloric aci free from iron, and using thejresulting wash liquor for chloride crystals.- v 4,

In test-imony whereof weaflix our signa- .HEINRIGH SPECKETER.

GUSTAV MUNCH.

ROSSTEUTSCHER.

Witnesses:

i l. H. AI TDtRSON,

Hilton Souue'rrnn'r,

Washing: a suhsequent hatch of aluminium 

